FIELD: physics; electricity.
SUBSTANCE: invention relates to electric measuring equipment and relay protection of power supply systems and increases speed of measuring insulation resistance and protection of electric network. Method is based on measurement of leakage current from auxiliary test voltage source in form of periodical sequence of pulses of type
where U1, U2 are voltage constants, U1 > U2, τ is time interval, T is test voltage pulses period, 
; measurement of leakage current I1 in time interval 
and leakage current I2 in interval T-T0 < t ≤ T, where T0 is voltage period of supply mains, 
, by averaging the voltage drop on the measuring resistance for the period of the supply network, calculating the insulation resistance by formula
where rt is the internal resistance of the source, comparing the obtained value with setting R0. In each measurement cycle voltage U1 is set equal to 
where rins0 is insulation resistance value measured in the previous cycle, current i(t) of network capacity charge is measured, threshold values 
and 
are calculated, current i(t) is compared to threshold values Ithr1 and Ithr2 and at 0 ≤ i(t) < Ithr1 test voltage is set u(t) = U2, and for Ithr2 < i(t) ≤ 0 value of voltage u(t) = -U2. When rins ≤ R0 of measurement is repeated n times and at sequential confirmation of insulation resistance decrease n times electric equipment is switched off.
EFFECT: technical result when implementing the claimed solution is increase of accuracy and speed of control of electrical resistance of insulation and protection of electric network.
1 cl, 5 dwg
